– Part III
Chapter 2 Database Environment
Review Questions
2.1 Discuss the concept of data independence and explain its importance in a database environment.
2.2 To address the issue of data independence, the ANSI-SPARC three-level architecture was
proposed. Compare and contrast the three levels of this model.
2.3 What is a data model? Discuss the main types of data models.
An integrated collection of concepts for describing and manipulating data, relationships between
2.4 Discuss the function and importance of conceptual modeling.
See Section 2.3.4.
2.5 Describe the types of facility you would expect to be provided in a multi-user DBMS.
Data Storage, Retrieval and Update Authorization Services
2.6 Of the facilities described in your answer to Question 2.5, which ones do you think would not be
needed in a standalone PC DBMS? Provide justification for your answer.
2.7 Discuss the function and importance of the system catalog.
2.8 Discuss the differences between DDL and DML? What operations would you typically expect
to be available in each language?
2.9 Discuss the differences between procedural DMLs and nonprocedural DMLs?
Procedural DML – A language that allows the user to tell the system what data is needed and
2.10 Name four object-based data models.
Entity-Relationship (ER)
2.11 Name three record-based data models. Discuss the main differences between these data
models.
relational data model – data and relationships are represented as tables, each of which
has a number of columns with a unique name
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2.12 What is a transaction. Give an example of a transaction.
2.13 What is concurrency control and why does a DBMS need a concurrency control facility?
2.14 Define the term “database integrity”. How does database integrity differ from database
security?
be
Exercises
2.15
functions that we would expect to be provided by a DBMS. What type of language does each
system provide? What type of architecture does each DBMS use? Check the accessibility and
extensibility of the system catalog. Is it possible to export the system catalog to another system?
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2.16 Write a program that stores names and telephone numbers in a database. Write another program
that stores names and addresses in a database. Modify the programs to use external, conceptual,
and internal schemas. What are the advantages and disadvantages of this modification?
The programs can be written in any suitable language and should be well structured and
2.17 Write a program that stores names and dates of birth in a database. Extend the program so that it
stores the format of the data in the database; in other words, create a system catalog. Provide an
interface that makes this system catalog accessible to external users.